The present invention relates to automatic dishwashers, and in particular to the removal of mineral deposits from interior surfaces of dishwashers.
Dishwashers are commonly used in both residential and commercial kitchens to clean and sanitize dishes, glassware, and cooking utensils. A problem that plagues dishwashers is the build-up of mineral deposits, especially calcium oxide commonly known as lime, on the interior components of the machine. The magnitude of this problem depends upon the mineral content of the water supplied to the dishwasher and whether water softening has been employed. Lime build-up is more significant in commercial dishwashers due to the frequency of use and the amount of water passing through the equipment. The lime deposits, often referred to as lime scale, has a negative impact on the ability of a detergent to satisfactorily clean the kitchenware. In addition, such mineral deposits may adversely affect movement of various dishwasher components and the proper flow of water.
As a consequence of this problem, products have been developed to dissolve calcium deposits within dishwashers. However these products have to be applied manually. Thus a dishwasher operator must first become aware that mineral deposits have developed to a degree that requires treatment. This means that the operator has to periodically inspect the dishwasher components for scale build-up.
The de-scaling process involves manually filling an empty dishwasher with water, adding the de-scaling chemical, and operating the machine through a rinse cycle. The manual de-scaling may require a longer than the several rinse cycles depending upon the degree of mineral build-up. In severe cases the dishwasher components have to be scrubbed by hand. It is not uncommon for kitchen personnel to spend 20 to 30 minutes cleaning a heavily limed dishwasher.
The present invention provides an apparatus which automatically operates a dishwasher to perform a de-scaling function at times when the dishwasher will not be required for normal operation. Preferably, repeated de-scaling operations occur at specified intervals or upon occurrence of a predefined event.
The dishwasher has a water valve, a drain valve, and a wash pump. The novel apparatus includes a reservoir for containing a de-scaling chemical which cleanses mineral deposits from surfaces of objects. Preferably, the reservoir contains a sufficient amount of the chemical for several de-scaling operations. A flow control device couples the reservoir to the dishwasher and controls a flow of the de-scaling chemical into the dishwasher.
A controller is connected to operate the water valve, the drain valve, the wash pump and the control device. The occurrence of a predefined event causes the controller to begin a process that removes the minerals from inside the dishwasher. For example that predefined event may be whenever a given number of days or a specified number of wash cycles have occurred since the last time the mineral removal procedure was performed.
To carry out that process the controller operates the water valve and the control device to introduce water and the de-scaling chemical into the dishwasher. Then the wash pump is activated for a given period of time to circulate the mixture of water and the de-scaling chemical inside the dishwasher. Thereafter the drain valve is opened to remove the mixture from the dishwasher.
Preferably the interior of the dishwasher is rinsed with water before and after the removal of mineral deposits to prevent a reaction of the de-scaling chemical with other chemicals used to clean kitchen ware.